Work is to be carried out on the parathyroid hormone (PTH) which governs the level of circulating Ca2 ion. Experiments are to be carried out to fully determine the sequence of nucleotides in the mRNA molecules which code for the precursor of PTH, i.e., preproPTH. The cDNA molecule developed for this purpose will be used as a probe to study the organization of PTH genes in the bovine and human genome. The following questions will be asked: how many genes are present: are there intervening sequences; are the DNA segments which code for the hydrophobic leader sequences of preproPTH used elsewhere in the genome? Finally, we would like to use the information about the organization of the PTH genome to study the mechanism of Ca2 ion regulation. Other experiments will be carried out on the parathyroid secretory protein, a molecule which is secreted parallel to PTH. We plan to sequence the mRNA, and learn something about its organization in the genome. We will ask whether it shares any of the regulatory apparatus in common with PTH.